Patent Reference 1 has disclosed an electrical connector as such a type of electrical connector. The connector disclosed in Patent reference 1 has terminals made of metal and having a flat over all shape, and plate surfaces of the terminals are arranged to be parallel to each other. Each of the terminals is provided with a fixing portion; an upper beam; a middle beam; and a lower beam, each having an arm shape and extending from the fixing portion in parallel in a same direction.
The fixing portion is inserted into a corresponding hole in a housing to be fixed thereto. The fixing portion supports a cam portion with an oval shape disposed on an actuator as a pressing portion member between the upper beam and the middle beam to be rotatable. A flexible wiring board, i.e., a type of flat cable, can be inserted into a space between the middle beam and the lower beam.
The upper beam has a high rigidity and is difficult to deform. The middle beam is easy to deform. In the connector disclosed in Patent Reference 1, after the flexible wiring board is inserted while the actuator is located at an open position, when the actuator is moved to a closed position, the cam portion of the actuator deforms the middle beam downwardly, so that an electrode portion of the middle beam elastically contacts with a corresponding circuit portion on an upper surface of the flexible wiring board.    [Patent Reference 1] Japanese Patent Publication No. 2002-93504
In the connector disclosed in Patent Reference 1, the upper beam has a high rigidity and is difficult to deform. Ideally, the upper beam is a rigid body. Elastic deformation for obtaining a contact pressure with the flexible wiring board relies only on the middle beam. That is, when the terminals as a whole are considered as a spring system, an elastic force, i.e., the contact pressure, is obtained through a single spring through deformation of the middle beams corresponding to a difference between a short diameter and a long diameter of the cam portion.
In Patent Reference 1, in order to obtain a deformation amount sufficient for obtaining the contact pressure, it is necessary to apply a large force to the middle beam as the single spring. That is, it is necessary to apply large force to the actuator. In other words, the terminals form a rigid spring system as a whole.